Re: [PATCH 25/25] ice9/attr: implement xattr-list procedure

[Andy Wingo]

Hello Dmitry :)

Thanks for this patch series.  As you can see it was a bit daunting to
review :)  Sorry for the delay.

I think the xattr work is probably most appropriate for a separate
library.  Guile doesn't currently bundle any modules that use the
dynamic FFI to bind C functions.  You can understand my hesitation to
take responsibility for ABI mismatches between Guile and a third-party
library that I don't know a lot about.  I think that a separately
packaged library would do a better job.

The (system foreign declarative) work looks really interesting.  We
definitely need a higher-level FFI.  I have some opinions here but I
don't have the cycles to hash them out :/  Basically I have had good
experiences with LuaJIT's ffi recently and would like to try something
like that some time.  It's especially wonderful for data.  I also think
that in Guile we should have the ability to tag bytevectors with a type,
so that we can access their fields in a nice way, so they print nicely,
and all that with just a couple words overhead per struct.  Maybe in
some cases we can even optimize it out.  It would be nice to have a path
towards no-allocation FFI data access in many cases.

But your code is really great too.  Different from what I was thinking
about, but well done.  That makes me think that we should not
incorporate anything into Guile at this time; rather we should encourage
people to experiment and build nice third-party high-level FFIs as
librarys, and encourage others to use those libraries, possibly even by
just copying them into users' source trees, to minimize dependency
hell.

What do you think?

Andy